Backyard Aquaponics
A place to discuss aquaponics

Still thinking about my system design and there's a number of questions I have revolving around plumbing I'd like to toss up to either make sure my thinking is correct (I'm the dummy), understand the thinking of other forum members, or perhaps find the ideas I haven't yet read in the forums and should have. Everything here is pertaining to flood and drain. I've read enough to know I don't want to do a raft system with a filter.

1. Some of you have growbeds linked in a serial fashion with a tank. If I understand this right, it's going to result in more nutrients for the plants in the first growbed, and much less in the last, right? If I don't want to be restricted on what I grow where, I should avoid this right?

2. Some of you have multiple growbeds linked in a parallel fashion with a tank. I *think* what you're doing here is branching several pipes off of a main feeder which I believe results in unequal amounts of water reaching each growbed. I think you're compensating for this with standpipes in each growbed and simply making sure you fill the beds long enough for the bed getting the least amount of water to be fully filled. Is this correct?

3. On your drain, some of you are using siphons, but most of you seem to acknowledge that standpipes are a better choice in most cases. With the standpipe, I think the design is that you have small holes near the base of the standpipe to get a slow drain (if it drains immediately, then the bed never gets flooded), with the pipe top ending at some maximum desired water level to facilitate really rapid draining should the bed fill to that point for some reason. Do the standpipes tend to exit through the bottom or the side (next to the bottom) of the growbed?

4. There seems to be an acknowledgment of issues with never fully getting the growbed drained during a drain. How much of an issue is this? Anyone solve it? Advantages/disadvantages to a level bed vs a bed with a slight incline?

5. Several of you seem to advocate having your tank drain into your beds instead of pumped into your beds. I think the thinking here is that solids are easier to pass through a nice big open tube vs through your pump. Is there any way to use a pump to pump water without the water actually passing through the pump? How big of an issue are solids for the pump? Any way to pass the solids through the pump without having a lot of cleaning to do?

6. How practical is it having the tank above the beds in a larger setup (800+ gallons)? Do you run a pipe to the bottom of the tank and have the pipe exit the tank at the "high water mark" and when the tank fills to that level it pushes water out the pipe to the beds? You seem to want to avoid "siphons" here if possible - what do you do if you need to run the pipe overhead to get to the beds so it's out of the way? Does that pretty much require a siphon or a pump at that point?

7. Those of you putting worms in your beds, do you have problems with them clogging up you pumps/pipes/whatever?

8. Not knowing what I'm doing, is it easy to come up with a filter of the right size to allow solids through while keeping fish out (even small fry)? With such a filter do you have problems with the filter getting clogged with fish or other stuff?

9. Is it thought that using a pump to go from a sump to a tank provides better aeration than beds that drain into a tank?

10. Anyone using a system with some sort of trigger to start the flood process again as soon as the bed empties? It sounds like flood and drain with some sort of almost continuous flow might be the best mix.

I'm sure I'll have more questions, but this should get things started so I can see how far off base I am or am not here.

Thanks!

I'll take a crack at it...

1. The nutrients are dissolved in water, so they are fairly even. If you are planted to capacity, then you may observe an effect like you describe. You can work with/around this by placing your heavy (tomato) and light feeders (lettuce) accordingly.


2. As long as each bed is flooded, it doesn't much matter. That's one of the huge advantages of flood and drain.

3. I actually have one of each design. Just depends on your physical setup and whatever is convenient.

4. Not an issue at all.

5. There are types of pump that do this, but they aren't the ones you'll find in your local shop. The solids are very small and are fine for most pumps. The CHIFT PIST arrangements traps most of the solids in the GB so they won't clog your pump.

6. If you are moving water up, that needs a pump or siphon, yes. Placing a large volume above the GBs, remember that only the top of the water needs to be above the GBs. So, depending on the geometry, your tank may be sitting on the ground or slightly elevated or highly elevated.

7. Never done it myself, but it seems there aren't any problems.

8. Hardware cloth does the trick for me. I've heard of people using cotton cloth and similar fine materials.

9. Doesn't affect DO results much either way.

10. There are a lot of ways to do that. Float switch is probably easiest calibrated to the water level the means your GBs are empty.

Sounds like you are making progress getting your head around things. Most of these questions are not uncommon so you are in good company


No this is not actually the case, the entire system tends to balance with nutrients so long as everything keeps mixing. When people have tested to see if the nutrients were stronger at the start of a run as opposed to the end of a run, they found the differences to not be measurable in a normal system set up so don't worry about this. As a side note though, in my system I've found that I can sometimes measure a trace of ammonia in the fish tank water but if I measure water coming out of a grow bed, the ammonia level is more likely to be 0. Anyway, don't worry yourself about this issue as it doesn't seem to be a problem in the average backyard system.


Most of us use ball valves to balance the inflow to multiple grow beds branching off of a main feed. Now it might be more efficient to get all the inlets level and make sure the same amount of pipe and all is leading to each bed but in the real world valves seem to work well enough.


I like siphons fine but if you want to use a timer and turn your pump on and off, stand pipes are pretty easy (provided you can find an appropriate timer and pump.)
Stand pipes can exit the bed either way, out the bottom is pretty common but out the side near the bottom can work too. It really all depends on your layout, the beds, the situation in general and the fittings you have to use and what the beds are made of etc.


My beds don't drain completely and it doesn't seem to be a problem so far. I would generally try and keep the top edge of the bed level (if it is sloping too much one end won't flood very deep and the other end might be overflowing over the side.) There might be some benefit to a slightly contoured bottom of the bed but I only if getting such a bed made won't put you over budget. I wouldn't worry too much over these issues.


Yes I definitely advocate the tank to growbeds to sump to pump flow of things. I didn't do that and I have to clean my pump trap every three days to keep flows good. Yes solids directly to the beds is a good thing, not just because the whole pump cleaning issue but also because solids that have not been blended up through the pump will be larger and easier to trap in the beds or separate out with a swirl filter.
Pumping without the solids/water passing through the pump. It can be done with an airlift pump but there are major limitations to what an airlift pump can do, it is mostly to do with how high the water can be lifted. Many commercial DWC systems operate with airlift pumps since they usually don't need to lift the water very high and they definitely need lots of air to run their systems but this wasn't the type of system you wanted to do.


Yep, you seem to have the jist of the SLO or solids lifting overflow-just be sure to have a T at the connection from the bottom of the tank to the horizontal out of the tank, that way you don't accidentally siphon the tank out. Also the Top of the T can act as an additional overflow in case something blocks up the bottom of the pipe.
No you can't run the pipe up higher than the high water level without adding more pumping or having to maintain water bridges that fail easily. You can however let the pipe drop down and go under pathways and come back up, I have done that in many places with great success in my system. The important part is the outlet must be lower than the high water mark in order for it to work. Flow rate depends on fall in gravity feed parts of the system.


Nope worms are wonderful! And FYI screens don't stop worms if they want to squeeze through, they will, but don't worry, they don't seem to be a problem living in your sump tank either.


The smaller the filter screen, the more often you need to check/clean it. (this is another reason I do like the CHIFT PIST set up, you don't need to worry as much about stuff clogging your pump but then again, you need to keep the fish from swimming out the overflow pipe so you have to have a grate or screen somewhere and it needs to be checked regularly. In a tank with only larger fish, a larger grate or whatever doesn't get clogged as much. If you have fry you want to protect in a system, I've used paint strainer bags to keep them out of the pump/plumbing. Things do get clogged but one way to prolong the interval between cleanings is to make the filter have as much surface area as possible.


It all depends on the set up. If running a system with a timer and slow drain from the beds back to the fish tank, I would probably add an air pump or some other means to continuously aerate the fish tank. It does depend on the type of fish though. Tilapia don't really need it unless heavily stocked but catfish and trout like more aeration.


There are different creative options for doing things sort of like this. You might want to look up the Barrel-Ponics manual and read over that one with it's Flush tank option. There are people playing with header tanks that would fill up before siphoning into a grow bed or they might use a FLOUT or another type of float valve. There are many options but they all add more complexity to the system. Timers and stand pipes are one simple way to manage flood and drain. Continuous pumping with siphons or FLOUTs are another simple way to do flood and drain. Siphons require properly balancing flow rates to the siphons to work properly. FLOUTs are far more forgiving of flow rates but they take up a fair bit of space in the grow bed. There are also systems that have pumps hooked to float switches but they are the least reliable option in my experience.



Nope you are not off base, all of these are common concerns. It sounds like you are getting the general idea and just need to work out the best method for yourself.

Good luck and keep up the good research.

"There are people playing with header tanks"

Actually I stopped "playing with it" about a month and a half ago TC it goes by itself; anyway I found something else to play with

So with parallel beds you just put a valve in front of each bed and then tweak each one to try and even out the water distribution better? I had thought the values were there for maintenance purposes.

Any good solutions for a fast drain from a bed once it's flooded so the flood/drain cycle can be sped up if desired?

Mention of an air lift pump sent me googling to figure out what it is and how it works. Along the way I found something that appears to be better;

http://www.geyserpump.com/principle.htm

If I want to drain my tank to my bed, and as a result I'm going with a really deep tank, what are the downsides here? I had thought that deep tanks should be avoided for aeration purposes, and I was unsure if fish stocking densities went down when I go vertical (assuming DO is the same in both situations).

TCLynx - care to go into detail as to why you don't like float switches? My only experience with them is the toilet tank (which has occasionally been a source of grief on a cheap toilet).

Thanks!

Check out barrelponics. Uses a water-filled weight to open a toilet flush valve that drains a lot of water fast. I've also found it injects outside air nicely into my covered fish tank....

[quote="gblack"]If I want to drain my tank to my bed, and as a result I'm going with a really deep tank, what are the downsides here? I had thought that deep tanks should be avoided for aeration purposes, and I was unsure if fish stocking densities went down when I go vertical (assuming DO is the same in both situations).
No real downsides except it being harder to see or catch your fish. Most aeration comes from disturbing the surface and from the growbed breathing rather than from transfer through the limited flat water surface. One thing you will find is that you get smaller temperature fluctuations and it will be easier to keep warm in winter.

Re pump clogging/solids: if you run a pump 24/7 the pump tends to suck things up that build up into a dam. In a timed system, the water in the line rushes back when the pump turns off, dislodging the solids and giving them another chance to pass through the pump without snagging on something. Folks with a 24/7 pump find that turning it off for a few minutes a day with a timer makes a big difference in clogging.

Re fry: a screen small enough for fry protection will clog very fast with the larger solid pieces larger fish produce. Besides, fry would get lost in a full-sized system. A couple options would be to raise fry in an aquarium to get them a bit larger or, even better, use happas (net baskets) in the big tank (or in the aquarium) with appropriately sized mesh for the fish size. These make it darned easy to check, move, feed, observe, etc as needed. One could probably keep 50 tilapia fry in a fine strainer until they double in size....

If you drop pipes to the floor to keep them out of the way, be sure you do not trap air in there between cycles or if the pump goes off. This air can form an air dam and block flow until your tank overflows. A good solution is to have a T fitting instead of an elbow where the pipe dives and put in an open vertical riser to release the trapped air.

The valves are also handy for maintenance purposes but that is not the only purpose.


Siphons can drain a bed quickly. A FLOUT can drain a bed quickly. A Flush valve set up kinda like in barrel-ponics could probably be adapted to drain a bed quickly.


yep there are some threads on here about geyserpumps


Deep tanks have some pros and cons. If you need to provide aeration with the use of an air pump, you need to get a pump that can handle pushing air down deeper so it needs to provide enough air at enough pressure to work with a deep tank. The other issue as already noted, a deep tank can be harder to reach into to net fish.


I've only really played with one float switch very much and it gets flaky regularly. It is one that the float actually pushes a physical switch up to turn the pump on and then when the water has dropped far enough the float is heavy enough to pull the switch back down when it hits the bottom of the guide. Well that is how it's supposed to work anyway but needs a tap regularly to get it to kick on. I've since tied a string to the support on the switch housing so that wind or a squirrel bumping the shade structure will help bump it along when I'm not near to notice that the bed is flooded for long enough.
Many of the other types of float switches I've seen require enough space for the float on a cable to move freely and I know they can get fouled easily and they often don't allow for enough level variation easily. Then many float switches use mercury which isn't something I want to introduce into a food system.

What I'm used to seeing on a toilet is usually a float valve which is a different thing. I've used a few types of float valves for topping up water into the system only when the water drops low enough to open the float valve. For this purpose I like using the plastic float valves commonly used for stock watering trough use.